The invention arose during development efforts relating to an SSB, spring set brake.
A spring set brake includes a magnetically permeable body having a pole face. An armature is axially movable toward and away from the pole face. An energization coil is energizable to magnetically attract the armature toward the pole face. A biasing member biases the armature away from the pole face. A pressure plate is spaced from the pole face by a plurality of legs. A friction disc between the armature and the pressure plate is keyable to an axially extending rotary shaft, such as a motor shaft. Upon de-energization of the coil, the biasing member biases the armature to a braking position pushing the friction disc against the pressure plate to stop rotation of the friction disc and the shaft. The armature in the braking position defines an air gap between the pole face and the armature. Upon energization of the coil, the armature is pulled toward the pole face to a released position releasing the friction disc and permitting rotation of the shaft.
The noted air gap is adjusted by machining the ends of the legs on one or the other of the pole face and pressure plate. This is time consuming and costly, particularly in precision applications because the magnetic air gap must be controlled within close tolerances to enable proper magnetive attractive force. These precision machining operations are undesirable from a manufacturing cost standpoint.
The present invention addresses and solves the noted problem and eliminates the objectionable high cost machining manufacturing steps. The invention provides a simple, cost effective structure and method for setting the magnetic air gap.
In another aspect of the invention, a simplified mounting arrangement for the pressure plate is provided.
In another aspect, axially extending line contact guide surface structure is provided minimizing magnetic flux leakage through the legs to the armature, and instead concentrating magnetic flux at the pole face to maximize magnetic force attracting the armature toward the pole face.
In another aspect, various mounting configurations are enabled in conjunction with a motor frame, including a first configuration with the pressure plate between the motor frame and the friction disc, and a second configuration with the pressure plate on the opposite side of the friction disc from the motor frame.
In another aspect, component part structure is provided for the magnetically permeable body. An annular ring member has legs extending integrally therefrom at one end, and is closed at the other end by a disc base member. The annular ring member has a plurality of internal pockets peripherally spaced therearound and mounting electronic components for the coil.
In another aspect, various configurations are provided for keying the friction disc to the shaft, including keyed hubbed and hubless versions.
In another aspect, an injection molded friction disc is provided.
In another aspect, a manual release mechanism is provided, having a first position permitting axial movement of the armature toward and away from the pole face under the influence of the energization coil and the biasing member, respectively, and having a second position holding the armature in the released position.
In another aspect, an energization coil is provided with a method and structure for simplified connection of wire ends.